Quoting Matthew Auld (2020-11-27 12:07:06)
From: CQ Tang cq.tang@intel.com
When cache_level is NONE, we check HAS_LLC(i915). But additionally for DGFX, we also need to check HAS_SNOOP(i915) on system memory object to use I915_BO_CACHE_COHERENT_FOR_READ. on dg1, has_llc=0, and has_snoop=1. Otherwise, we set obj->cache_choerent=0 and have performance impact.
Cc: Chris P Wilson chris.p.wilson@intel.com Cc: Ramalingam C ramalingam.c@intel.com Cc: Sudeep Dutt sudeep.dutt@intel.com Cc: Matthew Auld matthew.auld@intel.com Signed-off-by: CQ Tang cq.tang@intel.com
drivers/gpu/drm/i915/gem/i915_gem_object.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c index ddb448f275eb..be603171c444 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_object.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c @@ -95,6 +95,20 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj, mutex_init(&obj->mm.get_dma_page.lock); }
+static bool i915_gem_object_use_llc(struct drm_i915_gem_object *obj) +{
struct drm_i915_private *i915 = to_i915(obj->base.dev);if (HAS_LLC(i915))return true;if (IS_DGFX(i915) && HAS_SNOOP(i915) &&!i915_gem_object_is_lmem(obj))return true;return false;+}
/**
- Mark up the object's coherency levels for a given cache_level
- @obj: #drm_i915_gem_object
@@ -108,7 +122,7 @@ void i915_gem_object_set_cache_coherency(struct drm_i915_gem_object *obj, if (cache_level != I915_CACHE_NONE) obj->cache_coherent = (I915_BO_CACHE_COHERENT_FOR_READ | I915_BO_CACHE_COHERENT_FOR_WRITE);
else if (HAS_LLC(to_i915(obj->base.dev)))
else if (i915_gem_object_use_llc(obj)) obj->cache_coherent = I915_BO_CACHE_COHERENT_FOR_READ; else obj->cache_coherent = 0;
You must also define obj->cache_level correctly. You can not just assume the object will be snooped. -Chris --------------------------------------------------------------------- Intel Corporation (UK) Limited Registered No. 1134945 (England) Registered Office: Pipers Way, Swindon SN3 1RJ VAT No: 860 2173 47
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